With the remarkable development of information communication industry, needs for various memory devices are increasing. In particular, nonvolatile memory devices in which recorded data is not deleted even when power is cut off, are needed for portable terminals or MP3 players. A phase change random access memory (PRAM) device that uses a phase change phenomenon is being briskly researched as a nonvolatile memory device. Thus, a chalcogenide thin film in which a phase change phenomenon occurs, is being researched. Meanwhile, as semiconductor devices are highly integrated, a method of forming a chalcogenide thin film that has an excellent step coverage and an excellent gap-fill characteristic, in patterns having a large aspect ratio is required.
Conventional methods of forming a chalcogenide thin film may be performed by sputtering, chemical vapor deposition (CVD) or atomic layer deposition (ALD). When the chalcogenide thin film is formed by sputtering, a step coverage or gap-fill characteristic is deteriorated, and a small amount of carbon (C) or nitrogen (N) cannot be doped into the chalcogenide thin film. On the other hand, when the chalcogenide thin film is formed by CVD, the composition of patterns is not adjusted. In addition, when the chalcogenide thin film is formed by ALD, a deposition rate is reduced to about 0.3 Å/cycle and productivity is very low.